In this March 16, 2015 file photo U.S. Secretary of State John Kerry, left, listens to Iran's Foreign Minister Mohammad Javad Zarif, right, before resuming talks over Iran's nuclear program in Lausanne, Switzerland. The State Department said Kerry and Iran's Foreign Minister Mohammad Javad Zarif would meet Monday, April 27, 2015 at the United Nations on the sidelines of a conference on the nuclear non-proliferation treaty in which both men are participating. (AP Photo/Brian Snyder, Pool, File)